1. Subject of the Invention
This invention is generally directed to locks for retaining threaded nuts in secure engagement with threaded shafts and particularly to a locknut assembly for use with rotating shafts and components attached thereto wherein a spring locking member secures a locknut in fixed relationship to the shaft and which locking member exhibits a greater resistance to removal or slippage as portions thereof are continuously urged into locking engagement with the nut by centrifugal force as the shaft is rotated.
2. History of the Prior Art
Heretofore there has been a great deal of effort directed to provide locking means for securing nuts to the threaded ends of bolts and other structural members. In most prior art locknut assemblies, the locking means is generally provided by a wire or sheet metal member which is used to cooperatively engage both the nut and the shaft of a bolt upon which the nut is mounted. Although some locking members are the type which may deform the threads between the nut and the bolt many other prior devices do provide means for receiving the locking components by providing grooves along the length of the threaded portion of the bolt.
Examples of prior art locking devices which incorporate locking means which are receivable in grooves formed in the threaded ends of a bolt are U.S. Pat. Nos. 527,390 to Johnson; 753,301 to Obiols; 859,789 to Vaughn; 1,032,121 to Deuchler; 893,066 to Fletcher et al.; 287,003 to Cranford; 1,299,794 to Sheldon; and 348,117 to Ferber. In each of the foregoing references, a locking member such as a piece of sheet metal or wire has a portion thereof extending into an opening provided in the nut. The opening in the nut may in some cases be provided along the inner threaded portions such as shown in Fletcher, or may be made by forming a passage longitudinally with respect to the axis of the bolt through the nut as shown in Cranford. Each of the foregoing applications, however, is designed to retain the nut to a threaded portion of a bolt under generally static conditions, that is, in conditions where the bolt itself will not be subject to high-speed rotation or vibration which can cause an extremely high stress on the locked components.
In the field of turbo dynamics there is a need to insure that the components of a system are retained in proper engagement even where such parts undergo intense rotational movement such as in high-speed turbines. In addition, the locking means used must be sufficiently lightweight so that there will be no adverse affects on the rotating parts of the system to which the lock is attached. Such locks must also be strong enough to prevent movement of components, such as nuts, relative to other components, such as threaded shafts, under conditions where the centrifugal forces exerted on the elements of the lock are extremely intense. In the aforementioned prior art structures, the locking members or springs are not designed to counteract the forces created by rotation of the locked parts. With many of the prior art structures, the centrifugal force exerted on the locking member will cause a portion thereof to actually bring the lock out of engagement with the locked elements thereby making it possible for the locking member to be vibrated free of engagement therewith. In addition to the foregoing, vibration alone could act on other of the prior art structures discussed above wherein no means is provided for preventing the withdrawal of the locking member from its engagement between the locknut and the bolt or threaded shaft to which it is engaged.
Some prior art references, such as U.S. Pat. No. 883,691 to Baughman, do disclose locking means for securing a nut to a threaded shaft where a threaded shaft will be set in rotational movement during use. In Baughman, however, a spring element having a V-shaped beveled portion is shown as being receivable within a notch in the inner surface of the nut. The beveled portion permits a relative sliding movement of the locking member with respect to the nut where sufficient vibration is imparted to the locked assembly, and, therefore, a screw plug is placed through the locking member and into the rotating member in order to insure that the locking member is secured in place.